Various X-ray apparatuses for performing non-destructive inspection and the like at medical facilities, factories, etc. have been proposed (see PTL 1, for example).
The X-ray apparatus described in PTL 1 controls a filament current flowing through a filament arranged at a cathode part to control at a constant level a tube current flowing between the cathode part and an anode part with a target. As the filament thins and narrows due to deterioration, the resistance of the filament increases and the number of thermoelectrons emitted from the filament increases, so that the tube current increases. In this case, the X-ray apparatus performs control that decreases the filament current in order to maintain the increased tube current at a certain value.
This X-ray apparatus is capable of detecting deterioration of the filament from the amount of decrease in filament current. Generally, the life of a filament is approximately 30,000 hours, that is, the filament lasts about 3 to 5 years.
Meanwhile, some X-ray apparatuses suffer from a trouble of breakage of a filament after several hundred hours to several thousand hours. The X-ray apparatus of PTL 1 cannot predict such unexpected breakage of its filament.
Unexpected breakage of the filament suddenly renders the X-ray apparatus inoperable. In a case where the X-ray apparatus is used for, for example, pre-shipment inspection of industrial products or the like, unexpected breakage of the filament causes a trouble of stoppage of shipment of the industrial products.